Mining of clay and the like



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1.8. HIGHFIELD. MINING oF CLAY AND THE LlK'E.

APPLIQATIQN FILED NOV. 7, I9I9.

Patented Jan. 25,' 1921.

2 SHEETS-SHEET I.

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I.. S. HIGHFIELD.

` MINING-0F CLAY AND THE LIKE.

APPLICATION FILED NRV. 7.. 1,919- l l Pna Jan, 25,1921.

2 SHEETS-SHEET 2.

l UNITED STATES PATENT'oFFIcE.

JOHN SOiIERVILLE HIGHFIELD, OIE' LONDON,',ENGLND MINING OF CLAY AND THELIKE.

Specircation'of Letters ratent. Patented Jan. 25, 1921.

Application led November 7, y1919. Serial No. $88,278. Y

To allwltomitmy concern:

Be it known that I, JOHN SOMERVILLE Htorrrmm), a subject of the King ofGreat Britain, and residin at 36 Victoria street, London, S. W. 1,ngland, have invented certain new andA useful Improvements Relating tothe Mining of Clay and the like, of i which the following is aspecication.

This invention relates 'to the mining or quarrying of clay and the like,wherein the clay is washed out or mined by water suitably applied. Theobject of the 'invention 1s to provide a method whereby the c laysuspension in the water can be substantially 1ncreased withoutthickening the liquor, and consequently without the danger of choking ofthe valves and so forth of the pump ing apparatus. y

With the use of a suitable electrolyte, an aqueous suspension of acomparatively thin and liquid consistency can-be made containing over 25per cent., or even as much as50 per cent. by weight of clay substance,which without an electrolyte would form a sl1p of a thick cream-likeconsistency. Only a small uantity, sayv one-twentieth to onefifth di oneper cent. of the electrolyte,

^ reckoned on the weight of clay substance carried in suspension, isrequired., This represents the proportion Jfor caustlc soda. For heavierelectrolytes such as silicate of soda or carbonate of soda', thepercentage is correspondingly increased, so that the alkali containedtherein is in the same proportion.

The electrolyte such as silicate o soda is added to the water used inthe mining operation, and it serves to disperse the particles of clay inthe settling pit of the mine `or quarry so that for a given density ofliquor capable of being pumped and itransported, the percentage of claycarrled 1n suspension can be substantially increased. The addition ofthe electrolyte may be-made to the water before it is used in the miningoperation, or `in the settling pit or the like,

according to circumstances. By this method.

I am enabled to pump up in a given volume of liquor two or even threetimes as much clay as can be pumped by present methods without the useof an electrolyte. The suspensions made with the electrolyte can bepumped rapidly without rlsk, and the employment ofthis invention enablesthe cost of pumping to be substantially reduced as the total quantity ofliquor pumped for' a given yield is obviously in approximately quarry.'The exact method depends on the quality of the clay and on the methodof treatment desired. Most clays contain considerable quantities ofsilica and undecomf posed mineral matter such as feldspar; the mineralmatter may be in relatively large pieces or in the form of fine grains.The bulk of this matter may be removed at the bottom of the pit beforepumping the clay slip to the surface, or on the other hand, only thecoarser material may be removed atthe bottom of the pit' and the slipcontaining clay and mineral matter in a finer form pumped to thesurface. In the first instance, the tanks or pits can be used singly,butin the second case they require to be used in airs for example, asfollows Y ne of the tanks or pits is lled with the eiluent water whichis obtained from the surface of a tank aft'er the extraction of theclay, and the necessary quantity of electrolyte, which ma be sodiumsilicate or carbonate, is adde Thewater from this tank or pit is drawnoff by means of a pump, and 'l centrated, containing say 25 per cent. ofclayilsubstance. During this process some ofV the heavier material Willsettle out in the pit. The liquor is then run or pumped into a secondtank or pit where further settlin may take place to remove the inermateria The size of the tank or pit is determined by the length of timedesired for settlement. When settlement has been carried tothe desiredextent, the main pump is connected to the second settling tank or pitand the whole ofthe liquor containing the clay is pumped to the surfacefor further treatment in any known manner. Alternatively, 10

a main pit may be use'd from which the pumping is done continuously,this pit being provided with a stirrer-running continuously to preventfurther settlement; the liquor is then run from the second settling pitinto this main pumping pit.

When the process is completed in the first pit, the returned eiluent,while pumping from the first series of tanks or pits is being carriedout, may be run into a second pit to which the washing pump isconnected.

In any case a suflicient number of tanks or pits is used to enablecontinuous working to be carried out.

At suitable intervals, after the emptying of the settlingtanks or pits,the waste mineral matter accumulated therein may be removed. In someclays, the fine silica and other mineral matter is a useful byfproduct,and three or more settling tanks or pits may be used in a succession soas to grade the matter into various sizes, the heavier material settlingin the first pit, and the lighter material in the second, third andfourth pits for example.

The invention is illustrated inthe accompanying drawings, whereinFigures 1 and 2 are diagrams showing two somewhat dif# ferent modes ofcarrymg the invention into effect.

'In the arrangements shown in the annexed diagrams, 1 and 2 are mainsettling tanks or pits, and 3, 4, 5 and 6 are circulating tanks or pits.Any one of the tanks 3 to 6 can be connected to a pump 7 by means ofpipes 8 and cocks 9. The pump 7 delivers the liquor through pipes 10 tohydraulic nozzles 21 of any suitable known type used for mining orwashing out the clay at the face. The resulting l1quor containing theclay matter in suspension is carried away by suitable chutes or channelsto the duct 11 which leads through branching ducts back to any one ofthe tanks 3 to 6. The tanks 3 to 6 are used successively, the liquorbein circulated from tank 3 for example, throng 1 pump 7 to the clayface, and back through duct 11 to the same tank, until it contains asuspension of cla matter of the full desired concentration. hen thecirculation is continued, using tank 4, and so on, while tank 3 isdischarged throu h its cock 14 and duct 13 into the main sett ingtank 1. Later, the suspension collected in tank 4 is also dischar edinto pit 1, and is left to settle there- 1n. tanks 5 and 6 .have beensettlin meanwhile in pit or tank 2, and before ta 5 requires to bedischar ed again, the liquor from `pit 2 is drawn o throu h cock 16 andduct 17 to main pump 18 w ich delivers it to the treating plant.Ultimately, after settling for a suitable length of time, the suspensionfrom pit 1 is discharged through cock 15, duct 17 and pump 18 to thetreating plant. This plant may beof the electrohe suspensions collectedpreviously in A.osmotic type in whichA the suspended clay substance isde osited by an electric current,

or it may be o any other known type. The

plant shown inthe drawing is of vthe electroosmotic type and comprises atrough'20 in which a metal cylinder 24 revolves. Concentric with and atsome distance from the cylinder 24 a perforated metal electrode 25 isarranged, said electrode bein connected to the negative pole of anelectrlc generator 26, while the cylinder is connected to the positivepole thereof.v The clay sli is l that just described but includes a mainpitt 21 which is used when pumping is to be done continuously. A stirrer22 is arranged in the tank and runs continuously in order to preventsettlement. With this arran ement, the li uor. is run from the pits 1 an2- alternately into the main pit 21, and then pumped into 20. l

If the treating plant 20 is not an electrolytic one, the residual sodiumsilicate or the like used for the electrolyte, will generally bereturned unaltered in the eiiiuent in pipe 19, and will only require anaddition of a comparatively small amount of further silicate to brin itup to the required strength for re-use. f thev laut 20 is anelectrolytic one, and silicate ofpsoda is used as the electrolyte, onlythe alkaline base will be returned in the effluent liquor, and thepercentage of silica will require to be increased for example by' addingmore silicate of soda containing a maximum of silica in order to restorethe electrolyte to the properstrength. A somewhat similar result may besecured by usin peat water which contains humic acid, an which' reactswith the alkali in the eluent to give a suitable electrolyte. Ingeneral, the eiliuent when restored to its proper strength with theelectrolyte, will be just alkaline to phenol phthalein. When startingthe plant at first, it. will generally be correct to use about 10 poundsof silicate to 1,000 gallons of water in order to make up a liquor whichcontains the required proportion of electrolyte. The proportion willreadily be determined in any particular case by practical tests with theclay matter inl order to ascertain what pro rtion can be retained insuspension in t e liquor, and what its consistency is,

electro- Y It is important in order to avoid dilution ofthe electrolyte,to prevent the ingress of surface drainage water at the pits,particularly in wet weather and, where necessary, the pits are coveredor other precautions are taken to prevent the in ess of such w'ater, themine being drained y means of a drainage pit or pump drawing from a pitor tank reserved for this purpose preferably situated at a level belowthe other pits. Owing to the increased densi-ty of the l'electrolyte andcirculating slip as compared with water as generally used hitherto, themining operation with this slip is more ener etic and rapid than withthe usual Huid. he electrolyte also tends to render the clay matterimmediately capable of bein washed away in the liquor, the chemicaldlssolvin action thus facilitating the mechanical was ing action. Thequartz washed out with the clay matter tends to separate out morequickly than with the usual washi waters and a cleaner liquor isobtained, with less risk of fouling the pumps with foreign matter.

Another great point in the process is that whereas the amount of waterused up per ton of clay mined in the processes hitherto usual, has beenabout 30 tons, i. e. this is the normal wastage-of water, in the newprocess the amount used up is only about 4 tons or less of water per tonof clay mined. This is due to the increased concentration and thereduced pumping and so forth. The new process is 'available therefore inmany laces where clay mining has not been pro table hitherto owing tothe scarcity of water or the expense of conveying or pumping it to suchplaces.

Having thu-s described my invention what I claim as new and. desire tosecure by Letters Patent is 1. A method of mining clay' consisting inforcing a liquid in a stream against a clay face, collecting theresultant liquor in a collecting vessel and returning said liquor inthestream against the clay face until a desired degree of concentrationof clay suspension is attained in the liquor, allowing the resultantliquor to settle, and then pumping the liquor to a treating plant forextracting the clay from the liquor, the liquor rior to the pumpingoperation being ren ered electrolytic by means of a very smallpercentage of an. electrolyte adapted to insure the uniform dispersionof the clay particles in the liquor, whereby the suspension is renderedsubstantially thinner for a given percentae of clay carried in theliquor.

2. method of mining clay consisting in forcing a liquid in a streamagainst a clay 1 face, collecting the resultant liquor in a eollectingvessel and returning said liquor in the stream against the clay faceuntil a. desired degree of concentration of clay suspension is attainedin the liquor, passing the liquor into a settling plant, adding arelatively small precen O'e of an electrolyte to the liquor, allowin t eliquor to settle, and then pumping the iquor to a treating plant forextracting the clay from the liquor.

JOHN SOMERVILLE HIGHFIELD.

